I think it will be more than that between expulsions, resignations to follow the expelled and drop outs due to demoralisation. In particular, SWSS is going to be gutted.
But the real damage is going to be that they will be stumbling on demoralised, isolated and with a sullen and resentful minority still on board. Remember the Counterfire split, which was less significant than this, dragged on through a couple of years of mini splits. Back in the 70s, when a minority got expelled, it got expelled quickly and thoroughly, but more recently things have been a lot messier.
Still, there are too many variables to be certain about how this will go.